我不太确定为什么以下代码在 GCC 4.6.3 中给我以下错误
'boost::spirit::_a = boost::phoenix::function::operator()(const A0&) const [with A0 = boost::phoenix::actor >, F = make_line_impl 中的 'operator=' 不匹配, 类型名 boost::phoenix::as_composite, F, A0>::type = boost::phoenix::composite, boost::fusion::vector, boost::spirit::argument<0>, boost::fusion: :void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_, boost::fusion::void_ , boost::fusion::void_>]((* & boost::spirit::_1))'</p>
甚至可以将惰性函数对象的结果分配给 qi 占位符吗?
#include <string>
#include <boost/spirit/include/phoenix_function.hpp>
#include <boost/spirit/include/qi.hpp>
using std::string;
using boost::spirit::qi::grammar;
using boost::spirit::qi::rule;
using boost::spirit::qi::space_type;
using boost::spirit::qi::skip_flag;
using boost::spirit::unused_type;
namespace qi = boost::spirit::qi;
namespace phx = boost::phoenix;
struct make_line_impl
{
int* _context;
make_line_impl(int* context)
{
_context = context;
}
template <typename Sig>
struct result;
template <typename This, typename Arg>
struct result<This(Arg const &)>
{
typedef int* type;
};
template <typename Arg>
int* operator()(Arg const & content)
{
return new int(5);
}
};
template<typename Iterator>
struct MyGrammar : grammar<Iterator, unused_type, space_type>
{
rule<Iterator, unused_type, space_type> start;
rule<Iterator, int*(), space_type> label;
rule<Iterator, string*(), qi::locals<int*>, space_type> line;
MyGrammar() : MyGrammar::base_type(start)
{
make_line_impl mlei(new int(5));
phx::function<make_line_impl> make_line(mlei);
start = *(line);
line = label[qi::_a = make_line(qi::_1)];
}
};
int main(int argc, char **argv) {
string contents;
qi::phrase_parse(contents.begin(), contents.end(), MyGrammar<string::iterator>(), space_type(), skip_flag::postskip);
return 0;
}